March 19 (Bloomberg) -- The U.S. Federal Bureau of
Investigation joined Malaysia’s inquiry into the missing jet as
authorities sought to retrieve deleted data on a computer flight
simulator belonging to the plane’s pilot.

The FBI’s involvement, which was disclosed today by the
White House, widens the U.S. role in probing Flight 370’s
disappearance on March 8. The U.S. National Transportation
Safety Board and Federal Aviation Administration are already
working with Malaysian authorities, as is the U.S. military.

The search area for the Boeing Co. 777-200ER narrowed in
the southern Indian Ocean after an analysis of the plane’s
probable fuel reserves. Aircraft from Australia, New Zealand and
the U.S. patrolled a zone the size of Italy while the inquiry
into the simulator opened a new front in the mystery that began
March 8 when Flight 370 vanished with 239 people on board.

“The passengers, the pilots and the crew remain innocent
until proven otherwise,” Malaysian Acting Transport Minister
Hishammuddin Hussein said. “For the sake of their families, I
ask that we refrain from any unnecessary speculation that might
make an already difficult time even harder.”

Malaysia has brought in local and international experts to
examine the simulator, Hishammuddin said. Some data had been
deleted and “forensic work” to retrieve it was under way, he
said. The data log was cleared on Feb. 3, Khalid Abu Bakar, the
country’s police chief, said today.

Homes Searched

The homes of pilot Zaharie Ahmad Shah and co-pilot Fariq
Abdul Hamid were searched on March 15 after Prime Minister Najib
Razak said the Malaysian Airline System Bhd. plane was
intentionally diverted on March 8. It lost contact and
disappeared from radar screens less than an hour after it left
Kuala Lumpur bound for Beijing. Initial inquiries indicated the
copilot was last heard by air traffic controllers.

White House Press Secretary Jay Carney declined to comment
on the status of the investigation into Flight 370 while
confirming that the FBI was involved.

“We are finding that the level of cooperation with the
Malaysian government is solid,” Carney told reporters. “But I
have no update on the course of the investigation. It remains
the case that, you know, we are not in the position yet to draw
conclusions about what happened.”

U.S. Attorney General Eric Holder said earlier today that
the FBI is in regular consultations with Malaysian officials and
“we will make available whatever resources that we have.”

Fuel Analysis

Air patrols by the U.S., New Zealand and Australia will
resume tomorrow in the southern Indian Ocean, according to the
Australian Maritime Safety Authority.

An assessment by the NTSB allowed the search to be focused
on an area about the half the size of the zone planned
yesterday, according to John Young, the agency’s general manager
of emergency response. The search zone is about 305,000 square
kilometers (118,000 square miles).

A Royal Australian Air Force AP-3C Orion aircraft, which
made the first sortie to the area yesterday, covered about
65,000 square kilometers under good search conditions without
seeing any signs of debris, Young said.

“We still have grave fears for anyone that might have
managed to escape the aircraft in the southern ocean,” he said
in a video posted on the agency’s website. “It remains a big
area.”

Another Australian Orion was being added to the search
today alongside an Orion variant operated by the New Zealand Air
Force and a U.S. P-8 Poseidon surveillance plane, for a total of
four aircraft, Young said.

P-8 Flights

The U.S. P-8 will make one daily flight for three days
followed by a maintenance day, according to the Navy. It’s the
U.S.’s top maritime-search plane, capable of flying for eight to
nine hours at altitudes of 5,000 feet.

The search for the Malaysian jet, which lost contact with
air traffic control less than an hour after leaving Kuala Lumpur
at 12:41 a.m. on March 8 en route to Beijing, is the longest in
modern passenger-airline history. The previous record was the
10-day search for a Boeing Co. 737-400 operated by Indonesia’s
PT Adam Skyconnection Airlines, which went missing off the coast
of that country’s Sulawesi island Jan. 1, 2007.

The Boeing 777 was carrying 49.1 metric tons (54.1 tons) of
fuel when it departed Kuala Lumpur, for a total takeoff weight
of 223.5 tons, according to Subang Jaya-based Malaysian Air.

Roaring Forties

Much of the area Australia is scouring is within the
Roaring Forties, a region between the 40th and 50th degrees of
latitude south known for strong winds and wave conditions,
according to charts provided by the Australian Maritime Safety
Authority. That may diminish the chances of debris still being
afloat so long after the jet vanished.

Investigators are combing through data after the plane was
deliberately steered off its course and disappeared from radar.

The jet made its last satellite contact at 8:11 a.m. on
March 8, according to the prime minister. Malaysian officials,
who have said they can’t rule out hijacking or sabotage, are
also exploring the possibility of a pilot suicide.

The plane’s transponder beacon, which helps radar locate
aircraft more precisely, and a text-to-ground messaging system
were shut before Flight 370 turned off its course.

Satellite pings that weren’t turned off showed Flight 370
operated for almost seven hours after last making contact, Najib
has said. That may have taken the plane more than 3,000 miles
from where it was last tracked and pushed it to the limits of
its fuel load, if it was airborne the whole period.

Malaysia has received some radar data, according to
Hishammuddin, the transport chief, without elaborating on whom
it’s from and how it could affect the search.

Malaysia is assembling a team to send to Beijing to give
briefings and updates to the families of the plane’s passengers,
he said. Of the 239 people aboard the flight, 154 were from
mainland China.